Traditionally railway box-cars are spaced closely together such that the aerodynamic drag of the gap between them is relatively minor even at top speed. However with the in,teased use of standard intermodal (i.e., ship-rail-truck) freight containers, the length of which is less than that of standard flat-bed rail cars, the gap between consecutive containers on rail cars is significant as a fraction of container width,. As the gap between consecutive rectangular containers rises from zero to even as little as half the container width, the drag coefficient of the container rises markedly. Aerodynamic drag consumes a significant fraction of the energy required to move a train of intermodal containers, especially considering the relatively low rolling resistance of rail cars.